Who Turned On the A/C?!

Did everyone enjoy their vacation to Seattle? Wait, we weren't in Seattle? Hmm...interesting. Well if you're a stats kind of guy like me, yes...the weather over the past few days is what you would see on a normal mid-July day in the home of the Mariners and Seahawks. (The map above shows our temperatures as of 4:00 PM on July 21, and it looks like business as usual for now.)

This cool snap was not out of the blue, as we'd seen it coming during the week.

This was the 6-10 day outlook posted by the Climate Prediction Center for July 16-20. And boy was it right?! We weren't the only ones to feel Jack Frost's presence as he took a July vacation down south.

Folks from Kentucky down to Alabama clearly saw some of the coldest July high temperatures on record, and sometimes the models just can't handle the extremes. Knowing that a dramatic change in the weather pattern was looming, I decided to calculate the error in two forecast models (the GFS and NAM) that are initialized at 8 AM everyday for all of last week. Here were the results:

On the average, the models didn't do a bad job, going just a bit cooler than what was observed. But when it mattered, they choked like the 2004 New York Yankees. Friday, the day where much of the southeast experience record cool high temperatures, is the day where these model runs were at their worst, forecasting high temperatures way above what was observed. Lesson learned: Put more faith in the atmospheric dynamics at play, rather than the model outputs.

In another unusual string of events, it seems as though more cool weather is on the way NEXT week. An upper level disturbance is currently moving towards the Pacific Northwest, and is poised to take aim at our region early next week. Storms on Monday followed by a chill on Tuesday and Wednesday seem to be at play...for now. Here's what the Climate Prediction Center has to say in the current 6-10 day outlook:

And that may not be all, as more chill could be on the horizon later next week as well. It's too far out to tell if we'll see quite what we saw last week, but one thing is for sure: the record books have not had much time to collect dust recently.

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StormTrack 5 Team

The Tri-Cities has been home for Dave for more than 25 years. For more than two decades, he has been honing his skills on what he deems "a very challenging" part of the country to forecast the weather.